The goals of this study are twofold: 1. to verify and extend an experimental animal model for the study of pancreatic adenocarcinoma in which tumors are induced by the direct implantation of 7,12-dimethylbenz(a)-anthracene; 2. to test other chemicals for their carcinogenic potential when implanted into the pancreas. The morphology and behavior of the tumors will be characteized by correlated light and electron microscopy. Evidence of invasiveness and metastatic capabilities of the tumors will be examined. The cell(s) of origin of the tumor will be sought by studying early stages of tumor induction. The implantation model is well suited for such studies because the focus of carcinogenesis is in the area immediately adjacent to the implant. The implantation model has distinct advantages over those models employing systemic administration of large quantities of carcinogen. These advantages are: 1. the high incidence of tumors (80%); 2. the relatively short induction time (119 days); 3. the absence of primary tumors in other organs; for example, liver stomach, or lungs; 4. there is no impairment of immune and host defenses by systemic poisoning of the host animal; 5. there is no administration of large amounts of carcinogen with its attendant systemic toxicity. Tumors developed in this model will be compared with the hamster model and with human pancreatic adenocarcinoma. Several parameters of tumor induction will be investigated, including dosage level, method of implantation, alterations with increasing time, age of animals at the time of implantation, species differencies, and the effects of different carcinogens. Validation of the implantation, model will make possible further studies directed toward understanding the development of human pancreatic adenocarcinoma. It is anticipated that this model can be studied by methods employing cell culture, transplantation, and chemotherapy. The findings derived from this model should contribute to the general understanding of chemical carcinogenesis.